According to The Age newspaper, one of the men referred to the religious clothing after the women sat down next to them, saying: "You shouldn't be wearing that s*** in Australia."

Jason Cias, 36, claims an argument ensued, during which the older of the women spoke in Arabic to try and calm things down. The men then said: "You shouldn't be speaking that s*** in Australia."

As the women got off the train, one of the men shouted an apparent sexual threat. Mr Cias told The Age: "I said to the guy, 'Mate, they're women'. The implication there was you don't threaten people, particularly women."

It is the latest high-profile incident involving racism on public transport, and how Australians act to defend against it.

In April, Stacey Eden confronted a woman who was harassing a Muslim man and woman aboard a Sydney train:

Sydney woman defends Muslim couple from racist on train:
Sydney woman Stacey Eden has won international praise after coming to the defence of a Muslim couple who became the target of a racist rant on public transport.

Mr Cias said one of the unidentified men then punched him in the face, after which there was a short scuffle caught on camera by onlookers. Pictures and video evidence were passed to police.

Speaking later to News Limited, Mr Cias said the incident had left him with a "pretty good black eye" but insisted he'd do the same again. "If anything I wish I had intervened earlier," he said.

A spokesperson for Victoria Police said officers were investigating the incident, which occurred at about 3.30pm on a train bound for Craigieburn from Melbourne Central Station on 15 May. Witnesses were asked to contact Crime Stoppers.